There is a new version of the Haskell Ports Library available at http://www.cse.unsw.edu.au/~chak/haskell/ports/ It now has experiemental support for process management. You can create a process that gets its stdin from a lazy string and pumps its stdout and stderr into two ports. There are a couple of combinators that facilitate Unix-pipe-like behaviour and you can wait for the exit code of a subprocess in a single Haskell thread without blocking all the others. It's all quite a hackery and still pretty experimental, but as the subprocess management question did come up a couple of times recently, I thought I share what I have at the moment with the rest of you. Cheers, Manuel PS: This requires GHC as it relies on preemptive concurrency, exceptions, and the POSIX libs.